WO2018150528A1

WO2018150528A1 - Local oscillation device and array antenna device

Info

Publication number: WO2018150528A1
Application number: PCT/JP2017/005822
Authority: WO
Inventors: 浩之水谷; 英之中溝; 田島　賢一
Original assignee: 三菱電機株式会社
Priority date: 2017-02-17
Filing date: 2017-02-17
Publication date: 2018-08-23
Also published as: US20190393916A1; WO2018150767A1; JPWO2018150767A1; JP6399256B1; US10784911B2

Abstract

Conventionally, local oscillation devices operate all of a plurality of local oscillators regardless of a change in the requested signal-to-noise ratio according to conditions around a communication device; hence, when the requested signal-to-noise ratio is low, operation occurs at an excessive level of performance while maintaining a high state of power consumption. This local oscillation device is equipped with: a first local oscillator for outputting a first local oscillation wave which is synchronized with a reference signal, and switching the power supply on and off according to a control signal; a second local oscillator for outputting a second local oscillation wave which is synchronized with the reference signal, and switching the power supply on and off according to the control signal; and a path-switching circuit which is connected to the first and second local oscillators, and switches the paths of the first and second local oscillation waves according to the control signal or a signal which is synchronized with the control signal.

Description

Local oscillation device and array antenna device

The present invention relates to a local oscillation device and an array antenna device used for wireless communication, radar, and the like.

In recent years, there has been a growing demand for high-speed and large-capacity communication devices. In response to this demand, in recent years, beam forming technology aimed at increasing speed by narrowing radio waves toward specific users and suppressing radio wave interference has been developed. Development is actively underway. In order to perform beam forming, an array antenna in which a plurality of antennas are arranged is used.

As another technology for high-speed and large-capacity communication, multi-value modulation, that is, technology for increasing the amount of information that can be transmitted to the user at one time has been developed. However, there is a problem that it becomes weak against noise as the multi-level number of modulation is increased, and improvement of the signal-to-noise ratio has been a problem.

As one configuration for improving the signal-to-noise ratio, Patent Document 1 discloses a configuration in which an independent local oscillator is provided for each of a plurality of transmitters or receivers constituting an array antenna. Since the noise component (phase noise) included in the local oscillation wave output from an independent local oscillator is independent, if the signals output from multiple transmitters or receivers are synthesized, the desired signal component is amplitude synthesized. In contrast, the noise components are power combined. For this reason, the phase noise characteristic of the signal is improved and the signal-to-noise ratio is improved as compared with the configuration using a single local oscillator.

Japanese Patent No. 5377750

Communication devices are required to have low power consumption in addition to high speed and large capacity. Since the configuration described in Patent Document 1 uses a plurality of local oscillators, there is a problem that power consumption increases by the number of local oscillators.

There is a limit to the amount of information that can be transmitted and received simultaneously from one communication device. For example, when there are few users around the communication device, the communication speed per user can be increased by increasing the multi-value number of modulation. In this case, the demand for the signal-to-noise ratio for the communication device is high. Conversely, when there are many users around the communication device, it is necessary to reduce the communication speed per user by reducing the multi-value number of modulation. In this case, the signal to noise ratio requirement for the communication device is low.

When the configuration described in Patent Document 1 is used, all of the plurality of local oscillators are operating regardless of a change in the signal-to-noise ratio request according to the situation around the communication device. Therefore, when the signal-to-noise ratio requirement is low, there is a problem that the device operates with excessive performance while maintaining high power consumption.

An object of the present invention is to solve the above-described problems, and is an array that can change the power consumption of a local oscillation device in accordance with a change in the signal-to-noise ratio requirement according to the situation around the communication device. The purpose is to obtain an antenna.

The local oscillation device of the present invention outputs a first local oscillation wave synchronized with a reference signal, a first local oscillator that switches ON / OFF of a power supply according to a control signal, and a second local oscillator synchronized with the reference signal A signal that outputs a local oscillation wave and is connected to the second local oscillator that switches the power ON / OFF according to the control signal, the first local oscillator, and the second local oscillator, and is synchronized with the control signal or the control signal And a path switching circuit for switching the path of the first local oscillation wave and the second local oscillation wave according to.

According to the present invention, it is possible to change the power consumption of the local oscillation device in accordance with the change in the request for the signal-to-noise ratio.

It is a block diagram which shows one structural example of the array antenna apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the state of the local oscillation wave generation circuit 10 which comprises the array antenna apparatus which concerns on Embodiment 1 of this invention. It is a block diagram which shows the example of 1 structure of the array antenna apparatus which concerns on Embodiment 2 of this invention.

Embodiment 1.
1 is a block diagram showing an example of the configuration of an array antenna apparatus according to Embodiment 1 of the present invention.
This array antenna includes antennas 1a and 1b,

low noise amplifiers

2a and 2b,

filters

3a and 3b,

mixers

4a and 4b,

filters

5a and 5b,

amplifiers

6a and 6b, ADCs (Analog-to-Digital Converters) 7a and 7b ( An example of an analog-digital converter), a signal processing circuit 8, a reference oscillator 9, a local oscillation wave generation circuit 10, and a control signal generation circuit 14 are provided.

The local oscillation wave generation circuit 10 includes

local oscillators

11a and 11b, a path switching circuit 12, and

variable gain amplifiers

13a and 13b.

Antennas 1a and 1b are antennas that receive radio waves. The antennas 1a and 1b are antennas that receive radio waves transmitted by the user and output them to the

low noise amplifiers

2a and 2b, respectively. For example, a dipole antenna or a patch antenna is used for the antennas 1a and 1b.

The

low noise amplifiers

2a and 2b are amplifiers that amplify the signal to low noise, respectively. The

low noise amplifiers

2a and 2b are low noise amplifiers that amplify signals received by the antennas 1a and 1b to low noise and output the amplified signals to the

filters

3a and 3b. For example, the low-

noise amplifiers

2a and 2b include ICs (Integrated Circuits), ICs (Integrated Circuits), GaAs (Gallium-Arsenide), SiGe (Silicon-Germanium), CMOS (Complementary-Metal-Oxide-Semiconductor) and other integrated semiconductor processes. A hybrid IC in which components such as a capacitor are mounted on a substrate is used. The

low noise amplifiers

2a and 2b may be variable gain amplifiers that can vary the gain for amplifying the signal.

Filters

3a and 3b are filters that remove unwanted waves contained in the input signal and pass the desired waves. The

filters

3a and 3b remove unnecessary waves contained in the signals output from the

low noise amplifiers

2a and 3b, respectively, pass the desired waves, and output them to the

mixers

4a and 4b. For example, a band pass filter, a band rejection filter, a low pass filter, a high pass filter, or the like is used for the

filters

3a and 3b. The

filters

3a and 3b may be variable filters that can vary the signal band to pass or remove.

The

mixers

4a and 4b are mixers that mix a signal and a local oscillation wave and output the mixed wave. The

mixers

4a and 4b mix the signals output from the

filters

3a and 3b and the local oscillation wave output from the local oscillation wave generation circuit 10, respectively, and output the mixed waves to the

filters

5a and 5b. For example, as the

mixers

4a and 4b, a diode mixer using a diode, an FET mixer using an FET (Field Effect Transistor), or the like is used.

Filters

5a and 5b are filters that remove unwanted waves contained in the input signal and pass the desired waves. The

filters

5a and 5b remove unnecessary waves contained in the signals output from the

mixers

4a and 4b, respectively, pass the desired waves, and output them to the

amplifiers

6a and 6b. For example, a band pass filter, a band rejection filter, a low pass filter, a high pass filter, or the like is used for the

filters

5a and 5b. The

filters

5a and 5b may be variable filters that can vary the signal band to be passed or removed.

The

amplifiers

6a and 6b are amplifiers that amplify signals. The

amplifiers

6a and 6b are amplifiers that amplify the signals output from the

filters

5a and 5b and output the amplified signals to the

ADCs

7a and 7b. For example, for the

amplifiers

6a and 6b, an IC integrated by a semiconductor process such as GaAs, SiGe, or CMOS, or a hybrid IC in which components such as transistors, resistors, and capacitors are mounted on a substrate is used. The

amplifiers

6a and 6b may be variable gain amplifiers that can vary the gain for amplifying the signal.

ADCs

7a and 7b are ADCs that convert analog signals into digital signals. The

ADCs

7a and 7b convert the analog signals output from the

amplifiers

6a and 6b into digital signals, respectively. For example, ADCs such as a successive approximation type, a pipeline type, and a delta sigma type are used for the

ADCs

7a and 7b.

The signal processing circuit 8 is a signal processing circuit that obtains necessary information from the input digital signal by calculation. The signal processing circuit 8 obtains information included in the radio wave transmitted by the user from the digital signals output from the

ADCs

7a and 7b. In addition, a state switching signal for switching the state of the local oscillation wave generation circuit 10 is output to the control signal generation circuit 14 depending on whether the information has been correctly obtained. Here, the state of the local oscillation wave generation circuit 10 is the state shown in FIG. 2 described later, that is, the ON / OFF of the power supplies of the

local oscillators

11a and 11b constituting the local oscillation wave generation circuit 10, the local oscillator 11a, This state represents a combination of the output destination of the local oscillation wave output by 11b and the gains of the

variable gain amplifiers

13a and 13b. For example, the signal processing circuit 8 includes an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), a logical operation circuit, and the like.

The reference oscillator 9 is a reference oscillator that outputs a reference signal. The reference oscillator 9 outputs a reference signal for synchronizing the plurality of

local oscillators

11a and 11b. For example, a crystal oscillator, a MEMS (Micro Electro Mechanical Systems) oscillator, or the like is used as the reference oscillator 9.

The local oscillation wave generation circuit 10 is a circuit that outputs local oscillation waves to the

mixers

4a and 4b. The local oscillation wave generation circuit 10 includes a local oscillator 11a, a local oscillator 11b, a path switching circuit 12, a variable gain amplifier 13a, and a variable gain amplifier 13b. The local oscillation wave generation circuit 10 is synchronized with the reference signal output from the reference oscillator 9, and based on a plurality of control signals output from the control signal generation circuit 14 in response to a change in the signal-to-noise ratio requirement for the array antenna, It controls ON / OFF of the power supplies of the

local oscillators

11a and 11b, the output destination of the local oscillation wave output from the

local oscillators

11a and 11b, and the gains of the

variable gain amplifiers

13a and 13b.

The

local oscillators

11 a and 11 b are local oscillators that output local oscillation waves to the

mixers

4 a and 4 b via the path switching circuit 12. The

local oscillators

11a and 11b turn on / off the power based on the power supply control signal output from the control signal generation circuit 14, synchronize with the reference signal output from the reference oscillator 9, and route local oscillation waves to the

mixers

4a and 4b. Output to the switching circuit 12. The power supply control signal may be a signal for controlling ON / OFF of the power supply of the

local oscillators

11a and 11b, or a signal for controlling whether or not to turn on the power to the

local oscillators

11a and 11b. May be. That is, (1) the power supply circuit may be provided to the

local oscillators

11a and 11b so that “power supply control signal = signal for controlling ON / OFF of the power supply”, or (2) the control signal generation circuit 14 may be provided with the power supply circuit. The ON / OFF of the

local oscillators

11a and 11b may be controlled as “power control signal = voltage for driving the

local oscillators

11a and 11b”. For example, a PLL (Phase Locked Loop), a DDS (Direct Digital Synthesizer), or the like is used for the

local oscillators

11a and 11b.

The path switching circuit 12 is a circuit that switches the path of the local oscillation wave output from the

local oscillators

11a and 11b. The path switching circuit 12 switches paths based on the path control signal output from the control signal generation circuit 14 and changes the output destination of the local oscillation wave. For example, the path switching circuit 12 includes a switch, a signal distributor, a signal synthesizer, and the like.

The

variable gain amplifiers

13a and 13b are amplifiers that amplify the input signal by varying the gain according to the control signal output from the control signal generation circuit 14. The

variable gain amplifiers

13a and 13b amplify the signal output from the path switching circuit 12 with a gain corresponding to the gain control signal output from the control signal generation circuit 14, and output the amplified signal to the

mixers

4a and 4b. For example, as the

variable gain amplifiers

13a and 13b, an IC integrated by a semiconductor process such as GaAs, SiGe, or CMOS, or a hybrid IC in which components such as transistors, resistors, and capacitors are mounted on a substrate is used. .

The control signal generation circuit 14 is a circuit that generates a control signal in accordance with a signal output from the signal processing circuit 8. The control signal generation circuit 14 outputs a plurality of control signals for controlling the operation of the local oscillation wave generation circuit 10 to the local oscillation wave generation circuit 10 based on the state switching signal output from the signal processing circuit 8. Specifically, the control signal generation circuit 14 outputs a power supply control signal to the

local oscillators

11a and 11b, and changes ON / OFF of the power supplies of the

local oscillators

11a and 11b. The control signal generation circuit 14 outputs a path control signal to the path switching circuit 12 and switches the path of the local oscillation wave output from the

local oscillators

11a and 11b. The control signal generation circuit 14 outputs a gain control signal to the

variable gain amplifiers

13a and 13b to change the gain. For example, the control signal generation circuit 14 includes an FPGA, an ASIC, a logical operation circuit, and the like.

Next, the operation of the array antenna according to Embodiment 1 of the present invention will be described.

The antennas 1a and 1b receive the pilot signals (signals of a predetermined pattern) transmitted by the user and output them to the

low noise amplifiers

2a and 2b, respectively.

The

low noise amplifiers

2a and 2b amplify the signals received by the antennas 1a and 1b to low noise and output the amplified signals to the

filters

3a and 3b, respectively. The

filters

3a and 3b remove unnecessary waves contained in the signals output from the

low noise amplifiers

2a and 2b, pass the desired waves, and output them to the

mixers

4a and 4b, respectively.

The

mixers

4a and 4b mix the signals output from the

filters

5a and 5b. The

filters

5a and 5b remove unnecessary waves contained in the signals output from the

mixers

4a and 4b, respectively, pass the desired waves, and output them to the

amplifiers

6a and 6b.

The

amplifiers

6a and 6b amplify the signals output from the

filters

5 and 5b, respectively, and output the amplified signals to the

ADCs

7a and 7b. The

ADCs

7a and 7b convert the analog signals output from the

amplifiers

6a and 6b into digital signals, respectively. The signal processing circuit 8 obtains information included in the radio wave transmitted by the user from the digital signals output from the

ADCs

7a and 7b.

On the other hand, the reference oscillator 9 outputs a reference signal to the local oscillation wave generation circuit 10. The local oscillation wave generation circuit 10 outputs local oscillation waves synchronized with the reference signal output from the reference oscillator 9 to the

mixers

4a and 4b. Depending on whether the pilot signal transmitted by the user is finally processed by the signal processing circuit 8 and the target signal-to-noise ratio is satisfied, the signal processing circuit 8 Is output to the control signal generation circuit 14.

The control signal generation circuit 14 outputs a plurality of control signals for controlling the operation of the local oscillation wave generation circuit 10 to the local oscillation wave generation circuit 10 based on the state switching signal output from the signal processing circuit 8. Specifically, the control signal generation circuit 14 outputs power control signals to the

local oscillators

11a and 11b to control the power on / off of the

local oscillators

11a and 11b, and sends the path control signal to the path switching circuit 12. By outputting, the path of the local oscillation wave is switched, and by outputting a gain control signal to the variable gain amplifiers 13a and 13, the gains of the variable gain amplifiers 13a and 13 are changed. These control signals are all constituted by digital signals, for example, but may be analog signals.

FIG. 2 is a diagram showing a state of the local oscillation wave generation circuit 10 constituting the array antenna apparatus according to Embodiment 1 of the present invention. 2A and 2B, the path switching circuit 12 includes a signal distributor 15 and a switch 16.

FIG. 2A shows one of the states of the local oscillation wave generation circuit 10. The

local oscillators

11a and 11b are both powered on. The path switching circuit 12 connects the local oscillator 11a to the variable gain amplifier 13a and the local oscillator 11b to the variable gain amplifier 13b by switching the switch 16 to the local oscillator 11b side. Here, the

variable gain amplifiers

13a and 13b are both in a state where the gain is lower than that in FIG.

The state shown in FIG. 2 (a) is used when the signal-to-noise ratio requirement is high. For example, it is used when there are few users around the communication device and the multi-value number of modulation is increased in order to increase the communication speed per user. In this case, since the

local oscillators

11a and 11b output independent local oscillation waves, the noise components included in the digital signals output from the

ADCs

7a and 7b become independent from each other. Compared to a configuration using one local oscillator, the signal-to-noise ratio of the received signal can be increased by 3 dB.

FIG. 2B shows another state of the local oscillation wave generation circuit 10. Of the

local oscillators

11a and 11b, the local oscillator 11a is powered on, and the local oscillator 11b is powered off. The path switching circuit 12 connects the local oscillator 11a to both the variable gain amplifier 13a and the variable gain amplifier 13b by switching the switch 16 to the local oscillator 11a side, and the local oscillator 11b is opened. Here, the

variable gain amplifiers

13a and 13b have a higher gain than that in FIG.

The state shown in FIG. 2B is used when the signal-to-noise ratio requirement is low. For example, it is used when there are many users around a communication device, and the number of modulations is reduced to distribute limited resources, and the communication speed per user is reduced. In this case, by outputting the local oscillation wave from the local oscillator 11a, it is possible to suppress the power consumption for driving the local oscillator 11b while operating with the minimum signal-to-noise ratio. In the state shown in FIG. 2B, since the local oscillation wave output from the local oscillator 11a is distributed and output to the two

variable gain amplifiers

13a and 13b, the local oscillation wave input to each variable gain amplifier is The power is half of the state shown in FIG. Therefore, the gains of the two

variable gain amplifiers

13a and 13b are set to a state 3 dB higher than that in FIG.

Even if the circuit shown in FIG. 2 (c) is used instead of FIG. 2 (a), the same effect as in FIG. 2 (a) can be obtained. In FIG. 2C, the path switching circuit 12 includes a signal distributor 15, a switch 16, and a signal synthesizer 17. The switch 16 connected to the local oscillator 11b switches the path to the signal synthesizer 17 side. Since the

local oscillators

11a and 11b output independent local oscillation waves, the signal-to-noise ratio of the received signal can be improved as in the case of FIG.

Even if the circuit shown in FIG. 2D is used instead of FIG. 2B, the same effect as in FIG. 2B can be obtained. In FIG. 2D, since the switch 16 is not switched to the signal synthesizer 17 side, only the local oscillation wave output from the local oscillator 11 a is input to the signal synthesizer 17. In this case, since the local oscillator 11b is not powered on, power consumption for driving the local oscillator 11b can be suppressed. In addition, although the case where the switch 16 is an SPDT (Single | Pole | Dual | Throw) switch was demonstrated, the structure which uses two SPST (Single | Pole | Single | Throw) may be sufficient as long as two states can be switched.

Next, a procedure for switching the state of the local oscillation wave generation circuit 10 shown in FIG.

First, it is assumed that the local oscillation wave generation circuit 10 is in the state shown in FIG. When the pilot signals received by the antennas 1a and 1b are finally processed by the signal processing circuit 8 and the target signal-to-noise ratio is satisfied, the signal processing circuit 8 starts from the state of FIG. A state switching signal for switching to the state 2 (b) is output to the control signal generation circuit 14.

The control signal generation circuit 14 outputs a power supply control signal, a path control signal, and a gain control signal to the

local oscillators

11a and 11b, the path switching circuit 12, and the variable gain amplifier 13, respectively, from the state of FIG. Switch to the state of 2 (b).

In the state shown in FIG. 2B, when the pilot signals received by the antennas 1a and 1b are finally processed by the signal processing circuit 8, the target signal-to-noise ratio is satisfied. ), And the array antenna apparatus is operated with low power consumption, and then communication is started.

On the other hand, if the target signal-to-noise ratio is not satisfied, a state switching signal for returning from the state of FIG. 2B to the state of FIG. 2A is output to the control signal generation circuit 14. Thereafter, communication is started after maintaining the state of FIG.

As described above, according to the first embodiment, the

local oscillators

11a and 11b constituting the local oscillation wave generation circuit 10 are turned on / off and the

local oscillators

11a and 11b according to the request for the signal-to-noise ratio. Since the output destination of the local oscillation wave output from the signal and the gains of the

variable gain amplifiers

13a and 13b are changed, the power consumption of the local oscillation wave generation circuit 10 is changed in accordance with the change in the signal-to-noise ratio requirement. Can do.

In the above description, the case where there are two antennas (antennas 1a and 1b) for receiving signals has been described, but N may be used. When N antennas are used, N local oscillators are also required. In this case as well, a plurality of local oscillators can be operated with the minimum necessary power consumption by adaptively changing the number of local oscillators to be used in accordance with the request for the signal-to-noise ratio.

In the above description, the configuration using the same number of filters, amplifiers, and ADCs as the number of antennas has been described. However, it is also possible to combine the mixer outputs and use only one filter, amplifier, and ADC. Similarly, a configuration for synthesizing the output of the filter or a configuration for synthesizing the output of the amplifier may be used. In any configuration, a plurality of local oscillators can be configured by adaptively changing the number of local oscillators to be used. It can be operated with the minimum power consumption.

Embodiment 2.
In the first embodiment, the optimization of the power consumption of the local oscillation wave generation circuit used for the receiver has been described. In the second embodiment, optimization of power consumption of a local oscillation wave generation circuit used for a transmitter will be described.

FIG. 3 is a block diagram showing a configuration example of an array antenna according to Embodiment 2 of the present invention. 3, the same reference numerals as those in FIG. 1 denote the same or corresponding parts. This array antenna includes transmission antennas 1c and 1d, high-

power amplifiers

2c and 2d, filters 3c and 3d,

mixers

4c and 4d, filters 5c and 5d,

amplifiers

6c and 6d, DAC (Digital-to-Analog Converter) 7c and 7d. (An example of a digital-analog converter), a signal processing circuit 21, a reference oscillator 9, a local oscillation wave generation circuit 10, a control signal generation circuit 14, a reception antenna 25, and a receiver 26 are provided.

In FIG. 3, the transmission antennas 1c and 1d, high-

power amplifiers

2c and 2d, filters 3c and 3d,

mixers

4c and 4d, filters 5c and 5d, and

amplifiers

6c and 6d are different between the transmitter and the receiver. These correspond to antennas 1a and 1b,

low noise amplifiers

2a and 2b, filters 3a and 3b,

mixers

4a and 4b, filters 5a and 5b, and

amplifiers

6a and 6b, respectively, in FIG.

The signal processing circuit 21 is a signal processing circuit that outputs a digital signal by calculation and obtains necessary information by calculation from the input digital signal. The signal processing circuit 21 outputs a signal to be transmitted to the user to the DACs 7c and 7d as a digital signal. Further, information included in the radio wave transmitted by the user is obtained from the digital signal output from the receiver 26 by calculation. In addition, a state switching signal for switching the state of the local oscillation wave generation circuit 10 according to whether or not information has been correctly obtained is output to the control signal generation circuit 14. For example, the signal processing circuit 21 includes an FPGA, an ASIC, a logical operation circuit, and the like.

DACs 7c and 7d are DACs that convert digital signals into analog signals. The DACs 7c and 7d are DACs that convert the digital signal output from the signal processing circuit 21 into an analog signal and output the analog signal to the

amplifiers

6c and 6d. For example, ADCs of a resistance ladder type, a current output type, a delta sigma type, etc. are used for the DACs 7c and 7d.

The receiving antenna 25 is an antenna that receives radio waves. The receiving antenna 25 is a receiving antenna that receives radio waves transmitted by the user and outputs them to the receiver 26. For example, a dipole antenna or a patch antenna is used for the receiving antenna 25. The receiving antenna 25 may be the same as the antennas 1a and 1b shown in FIG.

The receiver 26 is a receiver that amplifies the input signal, removes unnecessary waves contained in the signal, converts the frequency of the signal into a frequency that can be processed by the signal processing circuit, and converts the signal into a digital signal. The receiver 26 amplifies the signal received by the receiving antenna 25, removes unnecessary waves included in the signal, converts the frequency of the signal to a frequency that can be processed by the signal processing circuit 21, converts the signal to a digital signal, and performs signal processing. Output to the circuit 21. The receiver 26 may be a receiver including the antennas 1a and 1b to

ADCs

7a and 7b, the reference oscillator 9, and the local oscillation wave generation circuit 10 shown in FIG. Alternatively, a configuration using a single local oscillator may be used. Although FIG. 3 shows a configuration in which one reception antenna 25 and one receiver 26 are used, a configuration in which N reception antennas 25 and N receivers 26 are used may be used.

Next, the operation of the array antenna apparatus according to Embodiment 2 of the present invention will be described.

The signal processing circuit 21 outputs a pilot signal transmitted to the user to the DACs 7c and 7d as a digital signal. The DAC 22 converts the digital signal output from the signal processing circuit 21 into an analog signal and outputs the analog signal to the

amplifiers

6c and 6d. The

amplifiers

6c and 6d amplify the signals output from the DACs 7c and 7d, respectively, and output the amplified signals to the

filters

5c and 5d.

Filters

5c and 5d remove unnecessary waves contained in the signals output from the

amplifiers

6c and 6d, respectively, pass desired waves, and output them to the

mixers

4c and 4d.

The

mixers

4c and 4d respectively mix the signals output from the

filters

5c and 5d and the local oscillation wave output from the local oscillation wave generation circuit 10, and output the mixed waves to the

filters

3c and 3d.

Filters

3c and 3d remove unnecessary waves contained in signals output from the

mixers

4c and 4d, respectively, pass desired waves, and output the high-

power amplifiers

2c and 2d.

The

high output amplifiers

2c and 2d amplify the signals output from the

filters

3c and 3d to high outputs, respectively, and output the amplified signals to the transmission antennas 1c and 1d. The transmission antennas 1c and 1d transmit signals output from the high-

power amplifiers

2c and 2d as radio waves to the user, respectively.

The user receives the pilot signals transmitted by the transmission antennas 1c and 1d, determines whether or not a desired communication quality is obtained, and transmits a response signal including the result to the reception antenna 25.

The receiving antenna 25 receives the response signal transmitted by the user and outputs it to the receiver 26. The receiver 26 amplifies the response signal received by the receiving antenna 25, removes unnecessary waves contained in the signal, converts the frequency of the signal to a frequency that can be processed by the signal processing circuit 21, and converts the signal to a digital signal. Output to the processing circuit 21.

The signal processing circuit 21 reads the content of the response signal from the digital signal output from the receiver 26 and controls a state switching signal for switching the state of the local oscillation wave generation circuit 10 according to whether or not a desired communication quality is obtained. The signal is output to the signal generation circuit 14. For example, the signal processing circuit 21 determines whether or not the user has received correctly depending on whether the value of a specific bit is “1” or “0” in the digital bit string obtained by demodulating the response signal. Here, the state switching signal is a signal for switching the state shown in FIG. That is, the ON / OFF of the power supply of the

local oscillators

11a and 11b constituting the local oscillation wave generation circuit 10, the output destination of the local oscillation wave output from the

local oscillators

11a and 11b, and the gains of the

variable gain amplifiers

13a and 13b. It is a signal for switching the state representing the combination. For example, the state switching signal is a 1-bit digital signal. If “HIGH”, the state shown in FIG. 2A is indicated. If “LOW”, the state shown in FIG. 2B is indicated.

The control signal generation circuit 14 outputs a plurality of control signals for controlling the state of the local oscillation wave generation circuit 10 to the local oscillation wave generation circuit 10 based on the state switching signal output from the signal processing circuit 21.

First, it is assumed that the local oscillation wave generation circuit 10 is in the state shown in FIG. When the user receives pilot signals transmitted from the transmission antennas 1c and 1d and a desired communication quality is obtained, the signal processing circuit 21 switches from the state of FIG. 2A to the state of FIG. 2B. Is output to the control signal generation circuit 14.

local oscillators

11a and 11b, the path switching circuit 12, and the

variable gain amplifiers

13a and 13b, respectively, from the state of FIG. Switch to the state of FIG.

In the state of FIG. 2 (b), when a desired communication quality is obtained as a result of the user receiving the pilot signals transmitted by the transmission antennas 1c and 1d, the state of FIG. 2 (b) is maintained, and the array antenna is maintained. Is operated in a low power consumption state, and communication is started.

Conversely, when the desired communication quality is not obtained, a state switching signal for returning from the state of FIG. 2B to the state of FIG. 2A is output to the control signal generation circuit 14, and thereafter Starts communication while maintaining the state of FIG.

As described above, according to the second embodiment, the local oscillator 11a and the local oscillator 11a included in the local oscillation wave generation circuit 10 according to the request for the signal-to-noise ratio of signals transmitted from the transmission antennas 1c and 1d to the user. Since the power supply of 11b is changed, the output destination of the local oscillation wave output from the

local oscillators

11a and 11b, and the gain of the

variable gain amplifiers

13a and 13b are changed, according to the change in the request of the signal-to-noise ratio, A plurality of local oscillators (

local oscillators

11a and 11b) can be operated with a minimum power consumption.

In the above description, the case where there are two transmission antennas has been described, but N may be used. When N antennas 1 are used, N local oscillators are also required. Also in this case, an array antenna that operates a plurality of local oscillators with the minimum power consumption can be obtained by adaptively changing the number of local oscillators to be used in accordance with the requirement of the signal-to-noise ratio.

In the above description, the configuration using the same number of DACs, amplifiers, and filters as the number of transmission antennas has been described, but the configuration may be such that the output of one DAC is distributed to a plurality of amplifiers. Similarly, a configuration in which only one DAC and amplifier is used to distribute the output of the amplifier to a plurality of filters, or a configuration in which only one DAC, amplifier and filter are used to distribute the output of the filter to a plurality of mixers. In any configuration, a plurality of local oscillators can be operated with a minimum power consumption by adaptively changing the number of local oscillators to be used.

1a 1b antenna, 1c 1d transmit antenna, 2a 2b low noise amplifier, 2c 2d high output amplifier, 3a 3b 3c 3d filter, 4a 4b 4c 4d mixer, 5a 5b 5c 5d filter, 6a 6b 6c 6d amplifier, 7a 7b A 7d DAC, 8 signal processing circuit, 9 reference oscillator, 10 local oscillation wave generation circuit, 11a 11b local oscillator, 12 path switching circuit, 13a 13b variable gain amplifier, 14 control signal generation circuit, 15 signal distributor, 16 switch, 17 Signal synthesizer, 21 signal processing circuit, 25 receiving antenna, 26 receiver.

Claims

A first local oscillator that outputs a first local oscillation wave that is synchronized with a reference signal, and that switches the power ON / OFF according to a control signal;
A second local oscillator that outputs a second local oscillation wave that is synchronized with the reference signal, and that switches ON / OFF of a power source in accordance with the control signal;
Connected to the first local oscillator and the second local oscillator, and switches the path of the first local oscillation wave and the second local oscillation wave according to the control signal or a signal synchronized with the control signal. A path switching circuit;
A local oscillation device comprising:
The path switching circuit outputs the first local oscillation wave and the second local oscillation wave, respectively, when the power supply of the second local oscillator is ON, and the power supply of the second local oscillator is OFF. 2. The local oscillation device according to claim 1, wherein the path is switched so that the first local oscillation wave is distributed and output in some cases.
The path switching circuit is
A signal distributor having a first input terminal, a second input terminal, and an output terminal connected to the first local oscillator; a first terminal connected to the second local oscillator; and the signal distributor A second terminal connected to the second input terminal and a third terminal which is an output terminal, and a switch for switching the connection;
The local oscillation device according to claim 2, further comprising:
The path switching circuit is
A signal synthesizer connected to the first local oscillator for synthesizing signals;
A switch connected to the second local oscillator and the signal synthesizer for switching the connection;
A signal distributor connected to an output terminal of the signal synthesizer and distributing an output signal of the signal synthesizer;
The local oscillation device according to claim 2, further comprising:
A local oscillation device according to claim 1;
A first antenna for receiving a first received signal;
A second antenna for receiving a second received signal;
A first mixer that mixes the first reception signal and the first local oscillation wave or the second local oscillation wave output from the local oscillation device and outputs a first mixed wave;
A second mixer for mixing the second received signal and the first local oscillation wave or the second local oscillation wave output from the local oscillation device and outputting a second mixed wave;
A first analog-to-digital converter that converts the first mixed wave into a first digital signal;
A second analog-to-digital converter that converts the second mixed wave into a second digital signal;
A signal processing circuit that processes the first digital signal and the second digital signal and calculates noise characteristics of the first received signal and the second received signal;
Control signal generation that outputs the control signal to the first local oscillator and the second local oscillator according to the noise characteristic calculated by the signal processing circuit, and outputs a signal synchronized with the control signal or the control signal Circuit,
An array antenna apparatus comprising:
A local oscillation device according to claim 1;
A signal processing circuit for outputting a digital signal;
According to the noise characteristics of the digital signal output by the signal processing circuit, the control signal is output to the first local oscillator and the second local oscillator, and the control signal or a signal synchronized with the control signal is output. A control signal generation circuit to
A first digital-to-analog converter for converting the digital signal into a first analog signal;
A second digital-analog converter for converting the digital signal into a second analog signal;
A first mixer that mixes the first analog signal and the first local wave or the second local wave output from the local oscillation device and outputs a first mixed wave;
A second mixer for mixing the second analog signal and the first local oscillation wave output from the local oscillation device or the second local oscillation wave and outputting a second mixed wave;
A first antenna for transmitting the first mixed wave;
A second antenna for transmitting the second mixed wave;
An array antenna apparatus comprising:
A receiving antenna that receives a response signal to the pilot signal output by the signal processing circuit;
A receiver for converting the frequency of the response signal;
With
The array antenna apparatus according to claim 6, wherein the signal processing circuit receives the response signal whose frequency is converted, and controls the control signal generation circuit according to a reception result.